Killing floor error message

[skylarlake135]

I installed killing floor and played it for 35 mins, and enjoyed it so much!!!
When I tried to play it the next day it gave me this message:
Build UT2004_Build_[2004-11-11_10.48]
OS: Windows NT 6.1 (Build: 7600)
CPU: GenuineIntel PentiumPro-class processor @ 1862 MHz with 3893MB RAM
Video: No Video
General protection fault!
History: UWindowsViewport::TryRenderDevice <- UWindowsViewport::OpenWindow <- UGameEngine::Init <- InitEngine <- FMallocWindows::Free <- FMallocWindows::Free


I tried to submit the bug report but my internet couldnt find the webpage.
I tried deleting the game and reinstalling it but it didnt work. I ocassionally get a runtime error message that comes up as well. I cant find my steam or killing floor files either to delete anything.

Please help, I would love to play this amazing game again.

[lyth]

Right click the game on steam, and click properties. Click local, and click "Validate Game Integrity". This will fix the issue. You may not have received all of the game files.

[skylarlake135]

I tried it three times and even uninstalled the game and reinstalled the game and did it again but I still keep getting the same message. I dont know if it matters but I purchased the game on a Gamestop App and installed it on the app before installing it on steam.